Setting up my store and am getting the following error on checkout:

10413 Transaction refused because of an invalid argument. See additional
error messages for details. - The totals of the cart item amounts do not
match order amounts.

I have logging enabled, sample log file below. Any help on a resolution appreciated:

May-14-2010 09:05:30
termEC-1
Killed the session vars as requested

May-14-2010 09:05:30
termEC-2
BEFORE: $this->showPaymentPage = 0
Token Data:

May-14-2010 09:05:30
termEC-3
AFTER: $this->showPaymentPage = 0

May-14-2010 09:05:30
termEC-8
$this->showPaymentPage NOT true, and NO custom page selected ... using SHIPPING as default

May-14-2010 09:05:30
termEC-10
Redirecting to checkout_shipping - Stack: checkout_shipping
Message: 10413 Transaction refused because of an invalid argument. See additional error messages for details. - The totals of the cart item amounts do not match order amounts.
Session Data: Array
(
[securityToken] => a4d48265b7c804812f301f58c8c4e549
[customers_host_address] => adsl-83-100-150-117.karoo.KCOM.COM
[cartID] =>
[cart] => shoppingcart Object
(
[observers] => Array
(
)

        [contents] => Array
            (
                [186] => Array
                    (
                        [qty] => 1
                    )

            )

        [total] => 2
        [weight] => 0.1
        [cartID] => 
        [content_type] => physical
        [free_shipping_item] => 0
        [free_shipping_weight] => 0
        [free_shipping_price] => 0
    )

[navigation] => navigationhistory Object
    (
        [observers] => Array
            (
            )

        [path] => Array
            (
                [0] => Array
                    (
                        [page] => index
                        [mode] => NONSSL
                        [get] => Array
                            (
                                [type] => ec
                                [token] => EC-8JR56441TL889291S
                                [PayerID] => TMUT5WKPZKJWN
                            )

                        [post] => Array
                            (
                            )

                    )

                [1] => Array
                    (
                        [page] => checkout_process
                        [mode] => NONSSL
                        [get] => 
                        [post] => Array
                            (
                            )

                    )

            )

        [snapshot] => Array
            (
                [page] => checkout_shipping
                [mode] => NONSSL
                [get] => Array
                    (
                    )

                [post] => Array
                    (
                    )

            )

    )

[check_valid] => true
[language] => english
[languages_id] => 1
[languages_code] => en
[currency] => GBP
[today_is] => 2010-05-14
[updateExpirations] => 1
[session_counter] => 1
[customers_ip_address] => 83.100.150.117
[new_products_id_in_cart] => 186
[valid_to_checkout] => 1
[cart_errors] => 
[payment] => paypalwpp
[customer_guest_id] => 5
[customer_id] => 5
[customer_default_address_id] => 5
[customer_first_name] => Donna
[customer_country_id] => 222
[customer_zone_id] => 15
[sendto] => 5
[billto] => 5
[shipping] => Array
    (
        [id] => rm1stpacket_rm1stpacket
        [title] => Royal Mail 1<sup>st</sup> Class <i style="font-weight: normal">"Packet"</i> (Great Britain and Northern Ireland only : 0.100 kg(s))
        [cost] => 1.14
    )

[shipping_tax_description] => VAT 17.5%
[shipping_tax_amount] => 0.2
[comments] => Thanks for sorting these out Darren. Regards, Pete Watson
[messageToStack] => Array
    (
        [0] => Array
            (
                [class] => checkout_shipping
                [text] => 10413  Transaction refused because of an invalid argument. See additional error messages for details. - The totals of the cart item amounts do not match order amounts. 
                [type] => error
            )

    )

)

=================================

Have you upgraded to v1.3.9 yet? It includes several fixes for that and related issues.

I'd just seen the post announcing the upgrade but was concerned about the need to to re-install all the payment and shipping modules.

However, as it's not working now I guess I need to bite the bullet and upgrade!

I'll do that now and retest.

Hmm I can see this isn't going to be a simple process <sob>

DarrenGriffin:

I'd just seen the post announcing the upgrade but was concerned about the need to to re-install all the payment and shipping modules.

However, as it's not working now I guess I need to bite the bullet and upgrade!

I'll do that now and retest.

Too easy mate, upgrade to 1.3.9b and the 10413 error is gone.

See these threads:
http://www.zen-cart.com/forum/showthread.php?t=134352
http://www.zen-cart.com/forum/showthread.php?t=85083&highlight=10413+error
http://www.zen-cart.com/forum/showthread.php?t=85643&highlight=10413+error